Lewin C. Powell III, the 16-year-old McDonogh School student who was charged last year with killing his mother with a baseball bat and trying to do the same to his father, intends to plead guilty to a single count of first-degree murder, the prosecutor and his lawyer said yesterday.

Powell was to have stood trial next week in Baltimore County Circuit Court on four charges in the May 2008 death of Donna Rosemarie Campbell-Powell, 39, an employee of the county Office of Budget and Finance, and the attempted murder of his father, Lewin C. Powell Jr.

Authorities said Campbell-Powell died after she was pummeled with a bat at their Towson home.

Powell had pleaded not guilty, stipulating that he was not criminally responsible - Maryland's equivalent of an insanity plea.

Shanell Kathleen Harleston, one of Powell's attorneys, said yesterday that she was negotiating a deal with prosecutors in which three of the charges would be dropped in exchange for a guilty plea to the remaining charge. She said the new plea would be filed today, with a hearing Monday before Judge Kathleen G. Cox.

"It was what we feel is in his best interests," Harleston said. "It's what he and his family decided," she added, referring to the father and aunt of the young man, who was charged as an adult.

Harleston said she did not expect her client to be sentenced during Monday's hearing but would ask the judge to defer punishment so that a presentencing investigation can take place.

Charles Gayle, the prosecutor handling the case, said the state intends to recommend a sentence of life with the possibility of parole.

"It is not possible at this point to say how long he would have to serve before he would be eligible for parole," Gayle said.

Parole for inmates serving life sentences in Maryland requires the approval of the governor, and no such inmate has been paroled since 1994.

Since the case will not go to trial, the prosecution will present a statement of facts Monday that will include Powell's confession and other evidence. Powell will have a chance to address the court, Gayle said.

"He has the right to explain his actions or ask for forgiveness," he said. "But, he might not say anything."

Other charges against Powell - attempted first-degree murder for a similar attack on his father and two counts of first-degree assault - will be dropped, Gayle said.

Shortly before the killing, authorities said, Powell and his mother had been arguing over his performance in school. The row escalated, and he attacked his mother with the bat, striking her in the head and body, police said later. Powell then hid her body in the family's garage, under a blanket, they said. At the time of the attack, no one else was in the house in the 1600 block of Alston Road in Riderwood.

The boy's father arrived home at midnight but was unaware of the attack, police said. The next morning, they said, Powell clubbed his father in the head, but the older man was able to overpower him.

Some of Campbell-Powell's co-workers went to her house to check on her after she failed to show up for work, police said. The door was locked, and they called police. When officers arrived, the father said, "Thank God you're here. My son killed my wife."

A next-door neighbor, Paul Kozloski, said in May that the teen's mother was a good neighbor but that she seemed too controlling and critical of her son.

"He had, for someone his age, the shortest leash you could have on a child," Kozloski said. "It was all about academics and sports, and it was pressure, pressure, pressure. ... I think he snapped."

The neighbor said one of his teenage daughters told him that Powell had expressed concern about informing his mother that he had earned a C in his Advanced Placement history class.

It was the second time in three months that a county teenager was accused of killing a parent. In February 2008, Nicholas W. Browning, a 15-year-old Dulaney High School sophomore, was arrested on murder and handgun charges in the deaths of his parents, John W. Browning and Tamara Browning, and his younger brothers, Gregory, 14, and Benjamin, 11.

Browning, now 16, pleaded guilty in October to the murders and is to be sentenced today.